The Challenge
A facility operated a single 250 kVA generator as backup power. The generator was critical — failure meant zero backup capacity during grid outages. The single-unit approach created a 'single point of failure' risk.
What Became Visible
Outage risk analysis revealed that if the 250 kVA unit failed, the facility had zero backup power during grid failure. The generator had failed once in 7 years (5 hour downtime). While relatively rare, the consequence of failure during a grid event would be complete production halt.
What Changed
Single 250 kVA generator replaced with two 125 kVA generators operating in parallel. Automatic load-sharing control ensures loads are balanced. If one unit fails, the other continues to supply all backup power.
How it worked: The two 125 kVA units were configured with synchronizing relays and load-sharing controls. During normal backup operation, load was shared 50-50. If one unit failed, the remaining unit was sized to handle full facility backup load (80–90 kW). The system eliminated single-point-of-failure risk.
Results
eliminates single-point failure
vs 25–35% on single large unit
from lower per-unit stress
zero backup capacity scenarios
Redundancy in backup power is risk management. Two smaller generators provide better reliability than one large generator, with the added benefit of better efficiency through higher load factors.
Operational Reality
Most mission-critical facilities eventually migrate to parallel backup systems after experiencing a backup-generator failure during a grid event.